An Essay Concerning Human Understanding
By
John Locke
Book IV:
Knowledge and Probability

THOUGH God has given us no innate ideas of himself; though he has stamped no original characters on our minds, wherein we may read his being; yet having furnished us with those faculties our minds are endowed with, he hath not left himself without witness: since we have sense, perception, and reason, and cannot want a clear proof of him, as long as we carry OURSELVES about us. Nor can we justly complain of our ignorance in this great point; since he has so plentifully provided us with the means to discover and know him; so far as is necessary to the end of our being, and the great concernment of our happiness. But, though this be the most obvious truth that reason discovers, and though its evidence be (if I mistake not) equal to mathematical certainty: yet it requires thought and attention; and the mind must apply itself to a regular deduction of it from some part of our intuitive knowledge, or else we shall be as uncertain and ignorant of this as of other propositions, which are in themselves capable of clear demonstration. To show, therefore, that we are capable of KNOWING, i.e. BEING CERTAIN that there is a God, and HOW WE MAY COME BY this certainty, I think we need go no further than OURSELVES, and that undoubted knowledge we have of our own existence.

2. For Man knows that he himself exists.

I think it is beyond question, that man has a clear idea of his own being; he knows certainly he exists, and that he is something. He that can doubt whether he be anything or no, I speak not to; no more than I would argue with pure nothing, or endeavour to convince nonentity that it were something. If any one pretends to be so sceptical as to deny his own existence, (for really to doubt of it is manifestly impossible,) let him for me enjoy his beloved happiness of being nothing, until hunger or some other pain convince him of the contrary. This, then, I think I may take for a truth, which every one's certain knowledge assures him of, beyond the liberty of doubting, viz. that he is SOMETHING THAT ACTUALLY EXISTS.

3. He knows also that Nothing cannot produce a Being; there ore SOmething must have existed from Eternity.

In the next place, man knows, by an intuitive certainty, that bare NOTHING CAN NO MORE PRODUCE ANY REAL BEING, THAN IT CAN BE EQUAL TO TWO RIGHT ANGLES. If a man knows not that nonentity, or the absence of all being, cannot be equal to two right angles, it is impossible he should know any demonstration in Euclid. If, therefore, we know there is some real being, and that nonentity cannot produce any real being, it is an evident demonstration, that FROM ETERNITY THERE HAS BEEN SOMETHING; since what was not from eternity had a beginning; and what had a beginning must be produced by something else.

4. And that eternal Being must be most powerful.

Next, it is evident, that what had its being and beginning from another, must also have all that which is in and belongs to its being from another too. All the powers it has must be owing to and received from the same source. This eternal source, then, of all being must also be the source and original of all power; and so THIS ETERNAL BEING MUST BE ALSO THE MOST POWERFUL.

5. And most knowing.

Again, a man finds in HIMSELF perception and knowledge. We have then got one step further; and we are certain now that there is not only some being, but some knowing, intelligent being in the world. There was a time, then, when there was no knowing being, and when knowledge began to be; or else there has been also A KNOWING BEING FROM ETERNITY. If it be said, there was a time when no being had any knowledge, when that eternal being was void of all understanding; I reply, that then it was impossible there should ever have been any knowledge: it being as impossible that things wholly void of knowledge, and operating blindly, and without any perception, should produce a knowing being, as it is impossible that a triangle should make itself three angles bigger than two right ones. For it is as repugnant to the idea of senseless matter, that it should put into itself sense, perception, and knowledge, as it is repugnant to the idea of a triangle, that it should put into itself greater angles than two right ones.

6. And therefore God.

Thus, from the consideration of ourselves, and what we infallibly find in our own constitutions, our reason leads us to the knowledge of this certain and evident truth, — THAT THERE IS AN ETERNAL, MOST POWERFUL, AND MOST KNOWING BEING; which whether any one will please to call God, it matters not. The thing is evident; and from this idea duly considered, will easily be deduced all those other attributes, which we ought to ascribe to this eternal Being. [If, nevertheless, any one should be found so senselessly arrogant, as to suppose man alone knowing and wise, but yet the product of mere ignorance and chance; and that all the rest of the universe acted only by that blind haphazard; I shall leave with him that very rational and emphatical rebuke of Tully (1. ii. De Leg.), to be considered at his leisure: 'What can be more sillily arrogant and misbecoming, than for a man to think that he has a mind and understanding in him, but yet in all the universe beside there is no such thing? Or that those things, which with the utmost stretch of his reason he can scarce comprehend, should be moved and managed without any reason at all?' QUID EST ENIM VERIUS, QUAM NEMINEM ESSE OPORTERE TAM STULTE AROGANTEM, UT IN SE MENTEM ET RATIONEM PUTET INESSE IN COELO MUNDOQUE NON PUTET? AUT EA QUOE VIZ SUMMA INGENII RATIONE COMPREHENDAT, NULLA RATIONE MOVERI PUTET?]